Method of protecting indicated information and cellular structure having its surface information protected by the protecting method

ABSTRACT

After displaying information ( 10 ) on the surface of an outer wall ( 4 ) of a cell structure, a portion surrounding the displayed information ( 10 ) is coated with a coating agent to form a region permeated with a coating agent ( 24 ) wherein pores ( 22 ) of the outer wall ( 4 ) are filled with the coating agent in a section of the outer wall ( 4 ) on which the information ( 10 ) is displayed. The region permeated with a coating agent ( 24 ) prevents a catalyst solution from exuding from the inside of the outer wall ( 4 ) of the cell structure. According to a method for protecting the displayed information and the cell structure of which surface information is protected by the protection method, a displayed information portion after loading catalyst components is prevented from being colored, and the displayed information can be maintained in a readable state.

TECHNICAL FIELD

The present invention relates to a method for protecting displayedinformation and a cell structure whose surface information is protectedby the protection method.

BACKGROUND ART

As an assembly for use in applications such as a catalyst converter foruse in a chemical reaction apparatus using exhaust gas purification andcatalyst functions of an internal combustion engine, a filter, and aheat exchanger, an assembly has been known in which a material ofcompressive elasticity having a cushioning property is disposed betweena cell structure and a cylindrical metal container (can member) and apredetermined compressive surface pressure is applied to the cellstructure via the material of compressive elasticity to accommodate andhold (canning) the cell structure in the metal container.

For example, when the assembly is used as the catalyst converter forpurifying a car exhaust gas, noble metals such as platinum, palladium,and rhodium are dispersed and loaded as a catalyst component in aceramic honeycomb structure as one type of the cell structures, and thisstructure is accommodated and held in the metal container (can member)via a ceramic mat and mounted in an exhaust system.

At this time, when the catalyst components are loaded in the cellstructure as described above, a loading amount changes with a weight ofthe structure. However, in order to control this loading amount, it isnecessary to correctly manage the weight of the cell structure in aloading process.

Moreover, the cell structure needs to be accommodated and held in themetal container in an appropriate state. However, since an outer shapedimension of the cell structure is correctly managed in the canningprocess, even a ceramic honeycomb structure having a large dimensionalfluctuation after firing can practically be used withoutmachining/processing an outer periphery of the structure.

Furthermore, the steps for manufacturing, loading, canning, and the likecan be traced back and recognized, by checking the lot number of thecell structure marketed after having been mounted in a car.

Therefore, for the cell structure, as shown in FIG. 2, an outer wall 4has been marked with useful information 10 such as the weight,dimension, characteristics, lot number, and manufacturing conditions.

The information 10 is practically used for smooth and efficientoperation of the production line, by reading it visually or mechanicallyby the users.

When the catalyst is loaded, in general, the catalyst components are notloaded by the outer wall of the honeycomb structure, and therefore themarked displayed information is not buried in the catalyst components.However, when the catalyst is loaded by applying it to the throughchannels in the cell structure, a solution containing a catalyst exudesto the outer wall of the cell structure by a capillary phenomenonthrough pores connected to one another, and an information displayedportion on an outer wall surface is also colored. In this case, theinformation is not easily read. When the information is not uniformlycolored or colored in a spotted manner, there is a problem that theinformation cannot be read in a mechanical read method requiringclearness as in image analysis.

To solve the problem, marking ink has been selected so that thedeveloped color of the displayed information obtains a sufficientcontrast with respect to the catalyst solution. However, the informationis colored mainly in various brownish colors from dark brown to black inaccordance with types or concentrations of the catalyst components.Therefore, it is difficult to handle all the catalyst solutions, andthis has been a factor for inhibiting automation of the marking.

The present invention has been developed in consideration of theabove-described conventional problems, and an object is to provide amethod for protecting displayed information, on which a displayedinformation portion is prevented from being colored after loadingcatalyst components and the displayed information can be maintained in areadable state, and a cell structure of which the surface information isprotected by the protection method.

DISCLOSURE OF THE INVENTION

According to the present invention, there is provided a method forprotecting displayed information, comprising the steps of: displayinginformation on the surface of an outer wall of a cell structure; andsubsequently coating a portion surrounding the displayed informationwith a coating agent to form a region permeated with a coating agentwherein pores of the outer wall are filled with the coating agent in asection of the outer wall on which the information is displayed, so thatthe region permeated with a coating agent prevents a catalyst solutionfrom exuding from the inside of the outer wall of the cell structure.

In the present invention, the coating agent is one wherein fine powdersare dispersed in a sol form in a liquid.

At this time, a concentration of the fine powder in the coating agent ispreferably 50% by weight or less, and the liquid is preferably water oran organic solvent.

Moreover, in the present invention, a particle size of the fine powderis preferably 10 to 30 nm.

At this time, the fine powder preferably comprises one or two or morematerials selected from a group consisting of silica, alumina, zirconia,and titania.

Furthermore, in the present invention, the information is preferablydisplayed in one or two or more display forms selected from a groupconsisting of characters, barcodes, and two-dimensional codes.

At this time, the information is preferably displayed in one or two ormore methods selected from a group consisting of a stamping method, inkjet method, thermal transfer method, and laser baking method. Theinformation is preferably displayed in ink.

It is to be noted that in the present invention the cell structurepreferably comprises one of the ceramic material selected from a groupconsisting of cordierite, alumina, mullite, lithium aluminum silicate,aluminum titanate, titania, zirconia, silicon nitride, aluminum nitride,and silicon carbide or a compound of two or more thereof.

Moreover, according to the present invention, there is provided a cellstructure of which surface information is protected by the protectionmethod described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a), (b) are explanatory views showing a honeycomb structure foruse in a cell structure according to an embodiment, (a) is a plan view,and (b) is a perspective view;

FIG. 2 is an explanatory view showing a marking method of a barcode byan ink jet apparatus; and

FIG. 3 is an explanatory view showing a state in which an outer wall ofthe honeycomb structure marked with information in the present inventionis coated with a coating agent.

BEST MODE FOR CARRYING OUT THE INVENTION

As described above, in a method for protecting displayed informationaccording to the present invention, after displaying information on thesurface of an outer wall of a cell structure, a portion surrounding thedisplayed information is coated with a coating agent. Accordingly, aregion permeated with a coating agent wherein pores of the outer wallare filled with the coating agent is formed in a section of the outerwall on which the information is displayed. The region permeated with acoating agent prevents a catalyst solution from exuding from the insideof the outer wall of the cell structure.

Accordingly, after loading catalyst components, a displayed informationportion is prevented from being colored, and the displayed informationcan be maintained in a readable state.

Here, in the present invention, the coating agent is one wherein finepowders are dispersed in a sol form in a liquid.

The coating agent is used to coat a portion surrounding marked displayedinformation 10 in an outer wall 4. As shown in FIG. 3, a regionpermeated with a coating agent 24 where pores 22 are filled with thecoating agent can preferably be formed in a section of the outer wall 4in the portion surrounding the displayed information 10.

The coating of the coating agent can be carried out by spraying,brushing, dropping, or impregnation.

At this time, in order to promote permeation of fine particles, aconcentration of the fine powder in the coating agent is preferably 50%by weight or less. However, since there is such a trouble that thenumber of the coatings is increased if the concentration of the finepowder is extremely low, the concentration is usually preferably about10 to 30% by weight.

Furthermore, the shape of the fine powder for use in the presentinvention should be spherical as much as possible and the particle sizethereof is 10 to 30 nm.

This is preferable because the fine powder can easily enter the pores ofthe outer wall of the cell structure without any hindrance. It is to benoted that the fine powder for use in the present invention is notespecially limited, but preferably contains one or two or more materialsselected from a group consisting of silica, alumina, zirconia, andtitania, and especially silica is preferable.

Moreover, the liquid for use in the present invention is preferablywater or organic solvent.

It is to be noted that the organic solvent is not especially limitedand, for example, methanol, isopropanol, xylene, n-butanol, methyl ethylketone, ethylene glycol, and dimethyl acetamide are preferablyappropriately selected and used, but it is more preferable to usealcohols which have little harm.

Here, a display form of the information is not especially limited, butthe information is preferably displayed in one or two or more displayforms selected from a group consisting of characters, barcodes, andtwo-dimensional codes (see FIG. 2).

The present invention is not especially limited to a method ofdisplaying the information in ink, and an effect of protecting thedisplayed information is obtained even in methods such as laser baking.

Also for these methods of displaying the information, two types ofmethods can be combined for use. For example, it is also possible tocombine and use both the display methods including an ink jet method ora thermal transfer method and a stamping method. When the information isdisplayed by ink, two types of ink such as heat resistant ink andnon-heat resistant ink may also be combined for use if necessary.

Moreover, it is preferable to use heat resistant ink when theinformation is displayed in the ink after loading the catalystcomponents, since the baking is carried out by subjecting to a heattreatment at about 400 to 800° C.

Furthermore, since the catalyst components are generally loaded on asubstrate in the form of an aqueous solution, the ink preferably haswater resistance.

For example, as shown in FIGS. 1(a), (b), the cell structure ispreferably a honeycomb structure which includes a plurality of cellpassages 3 formed by a plurality of partition walls 2 and in which acell partition wall thickness is 0.11 mm or less and an open frontalarea ratio is 85% or more.

Moreover, the honeycomb structure includes the outer wall 4 formingouter-diameter contour around the structure, and the thickness of theouter wall is preferably at least 0.05 mm.

Furthermore, as the cell structure for use in the present invention, inaddition to the honeycomb structure, a foam structure may also be used.

It is to be noted that the cell structure for use in the presentinvention preferably contains one or two or more of ceramic materialsselected from a group consisting of cordierite, alumina, mullite,lithium aluminum silicate, aluminum titanate, titania, zirconia, siliconnitride, aluminum nitride, and silicon carbide or of a compound thereof.The adsorption material selected from a group consisting of activecarbon, silica gel, and zeolite can also preferably be used for the cellstructure.

Moreover, as to the cell shape for the honeycomb structure formed byextrusion molding, there are triangular, quadrangular, hexagonal, andround shaped cells. In general, the structure having square shaped cellsas one of quadrangular shaped cells is frequently used. However, inrecent years, the use of the honeycomb structure having hexagonal shapedcells has also spread.

The present invention will further be described hereinafter in detailbased on examples, but the present invention is not limited to theseexamples.

EXAMPLES 1 TO 12, COMPARATIVE EXAMPLES 1 TO 5

After measuring an outer diameter of a cordierite honeycomb structure (2mil partition wall, cell density of 900 cpsi, nominal outer diameter ofφ106 mm, length of 114 mm) with a measurement apparatus, as shown inFIG. 2, a honeycomb structure 1 discharged from the measurementapparatus was next sent to an ink jet apparatus 13, and the outersurface of the honeycomb structure 1 was marked with a barcode based onthe information simultaneously sent.

At this time, examples of conditions for the marking by ink jet are asfollows.

[Example of Ink Jet]

Ink Jet Apparatus:

-   -   Emerge Co. S4 Plus        Type of Ink:    -   Heat resistant ink (dark brown at room temperature, orange after        the heat treatment)        Form of Information Laid on the Honeycomb Structure:    -   Numeric characters        Information Laid on the Honeycomb Structure:    -   Average outer-diameter of the honeycomb structure by actual        measurement (strikethrough: and actual measurement mass value)

After the printing on these conditions, a frame larger in length andbreadth than the marked information by about 5 mm was prepared, and thecoating agent shown in Table 1 was used in the frame to apply thecoating (twice) (see FIG. 3). After the catalyst components were loadedby the honeycomb structure, it was checked if it was possible torecognize the information by image analysis. As Comparative Example 1,an uncoated sample was used. TABLE 1 Catalyst Material Concentra-solution By image treatment of Particle tion of exudation Character finesize Particle Solution fine powder preventive distinction Matchingpowder (nm) shape [solvent] (wt %) effect rate (%) rate (%) Example 1Silica 10-20 Spherical Water 10 Good 98 88 Example 2 Silica 10-20Spherical Water 20 Satisfactory 100 99 Example 3 Silica 10-20 SphericalWater 40 Good 96 83 Example 4 Silica 10-20 Spherical Methanol 30Satisfactory 100 98 Example 5 Silica 20-30 Spherical Methanol 40Satisfactory 100 95 Example 6 Silica 10-20 Spherical Methyl 30Satisfactory 100 97 ethyl ketone Example 7 Silica 10-20 SphericalEthylene 20 Satisfactory 100 97 glycol Example 8 Silica 10-20 SphericalDimethyl 20 Satisfactory 100 96 acetamide Example 9 Silica 10-20Spherical Isopropanol 30 Satisfactory 100 97 Example 10 Silica 10-20Spherical Xylene-n- 30 Satisfactory 100 95 butanol Example 11 Alumina10-20 Bar-shaped Water 20 Good 95 81 Example 12 Silica 10-20 SphericalWater 50 Satisfactory 50 30 Comparative — — — — — — 45 30 Example 1Comparative Alumina 100 × 10  Feathery Water 10 Disapproved 48 29Example 2 Comparative Magnesia 250-350 Particulate Water 20 Disapproved51 30 Example 3 Comparative Titania 100 Spherical Water 20 Disapproved47 28 Example 4 Comparative Zirconia  50 Spherical Water 20 Disapproved55 31 Example 5

From results of Table 1, in any of Examples 1 to 12, the catalyst wasnot permeated in the outer wall marked with the information in a processfor loading by catalyst solution, therefore the information clearlyremained, and a character recognition rate by image analysis was 95% ormore.

On the other hand, in Comparative Example 1, especially for theinformation colored in the spotted form, it was impossible to recognizethe information by image analysis, and the character recognition ratewas about 45%.

Furthermore, in Comparative Examples 2 to 5, since the particle size ofthe fine powder in the coating agent was excessively large, it wasimpossible to charge the fine particles into pores in the outer wallwell, the information was colored, and the character recognition rate byimage analysis was 47 to 55%.

INDUSTRIAL APPLICABILITY

In a method for protecting displayed information and a cell structure ofwhich surface information is protected by the protection methodaccording to the present invention, a displayed information portion isprevented from being colored after loading catalyst components, and thedisplayed information can be maintained in a readable state.

1-11. (canceled)
 12. A method for protecting displayed information,comprising the steps of: displaying information on the surface of anouter wall of a cell structure; and subsequently coating a portionsurrounding the displayed information with a coating agent to form aregion permeated with a coating agent wherein pores of the outer wallare filled with the coating agent in a section of the outer wall onwhich the information is displayed, so that the region permeated with acoating agent prevents a catalyst solution from exuding from the insideof the outer wall of the cell structure.
 13. The method for protectingthe displayed information according to claim 12, wherein the coatingagent contains a fine powder dispersed in a sol form in a liquid. 14.The method for protecting the displayed information according to claim13, wherein a concentration of the fine powder in the coating agent is50% by weight or less.
 15. The method for protecting the displayedinformation according to claim 13, wherein a particle size of the finepowder is in a range of 10 to 30 nm.
 16. The method for protecting thedisplayed information according to claim 13, wherein the fine powdercomprises one or two or more materials selected from a group consistingof silica, alumina, zirconia, and titania.
 17. The method for protectingthe displayed information according to claim 13, wherein the liquid iswater or organic solvent.
 18. The method for protecting the displayedinformation according to claim 12, wherein the information is displayedin one or two or more display forms selected from a group consisting ofdisplay forms of the information such as characters, barcodes, andtwo-dimensional codes.
 19. The method for protecting the displayedinformation according to claim 12, wherein the information is displayedin one or two or more methods selected from a group consisting of astamping method, ink jet method, thermal transfer method, and laserbaking method.
 20. The method for protecting the displayed informationaccording to claim 12, wherein the information is displayed in ink. 21.The method for protecting the displayed information according to claim12, wherein the cell structure comprises a ceramic materials selectedfrom a group consisting of cordierite, alumina, mullite, lithiumaluminum silicate, aluminum titanate, titania, zirconia, siliconnitride, aluminum nitride, and silicon carbide or a compound of one ortwo or more thereof.
 22. A cell structure, wherein surface informationis protected by a method for protecting displayed information,comprising the steps of: displaying information on the surface of anouter wall of a cell structure; and subsequently coating a portionsurrounding the displayed information with a coating agent to form aregion permeated with a coating agent wherein pores of the outer wallare filled with the coating agent in a section of the outer wall onwhich the information is displayed, so that the region permeated with acoating agent prevents a catalyst solution from exuding from the insideof the outer wall of the cell structure.